Commutator for dynamo-electric machines



E. D. PRIEST! COMMUTATOR FOR DYNAMO ELECTRIC MACHHJES. APPLlCATlON FILED DEC. 17, m7.

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UNITED STATES PATENT OFFICE.

EDWARD D. PRIEST, OF SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

COMMUTATOR FOR DYNAMO-ELECTRIC MACHINES.

Specification of Letters Patent.

Patented Aug. 17, 1920.

Application filed December 17, 1917. Serial No. 207,517.

To all whom it may concern Be it known that I, EDWARD D. PRIEST, a citizen of the United States, residing at Schenectad in the county of Schenectady, State of NEW York, have invented certain new and useful Improvements in Commutators for Dynamo Electric Machines, of which the following is a specification.

My invention relates to an improvement in commutators for dynamo electric machines, and particularly to an improved manner of connecting the armature leads to the segments of the commutator.

In the operation of certain dynamo electric machines, such as railway motors, trouble has been heretofore experienced from the breaking of armature leads at the point of attachment to the commutator segments, due to the vibration of the leads, causing them to bend back and forth until they finally break in two.

The object of. my invention is to reduce to a minimum the vibration of the leads, so as to render their breakage less likely, and at the same time, to provide means whereby the machine will still be operative even though one of the leads does break.

My invention will be more fully explained in connection with the accompanying d rawing, in which Figure 1 shows a sectional View of a portion of a commutator arranged in accordance with my invention and Fig. 2 shows a modification thereof.

Referring to the figures of the drawing, 1 is a commutator segment of a commutator 2 of a dynamo electric machine provided at one end with the usual lead receiving slot in which a pair of armature leads 3 are fastened. The end of the segment, to which the leads are fastened, is cut away, either by chamfering as illustrated at 4 in Fig. 1, in which case the chamfer is at any angle to the direction in which the leads enter the segment, or by the step arrangement as illustrated at 5 in Fig. 2. By either of these arrangements the leads will be attached to the segments in difl'erent tranverse planes. Consequently they will be of different lengths and their natural period of vibration will be different, so that they will no longer tend to vibrate together. In this way the vibration of the leads will be dampened out to a considerable extent. The tendency of both leads to break at the same instant is thus greatly reduced. This is especially true of the construction shown in Fig. 1, because, in addition to the differ ence in lengths of the two armature leads, the line at which breakage naturally tends to take place, is along the line of the chamfering which involves longer cross sections of the leads where they are joined to the commutator segment, the point of bending also being less well defined as the leads enter the segment on a sloping line.

In order to still further reduce the tendency of-the leads to break, and, at the same time, have the machine still operative in case one of the leads does break, I connect the two leads together, both mechanically and electrically and independently of the commutator, by a band 6 soldered around them. The band 6 is spaced" :1 sufficient distance from thecommutator to permit of the usual flexibility at the point of connection to the segment.

With this arrangement of the segments and leads, the tendency to breakage is still further reduced, for the reason that the band 6 will tend to further reduce the vibration of the leads because one lead tends to support the other to a certain extent, and at the point where one wire is apt to break off, the other is in a position to bend. Should one of the leads break, the operation of the machine will not be effected, since the band 6 connects the armature coils independently of the commutator and there will be no open circuit unless both leads break.

I have illustrated and. described my invention as embodied in what I now consider the preferred forms, but the arrangement is susceptible of further modification and I therefore aim in the appended claims to cover all such modifications as lie within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a commutator for dynamo electric machines. a commutator segment provided at one end with a lead receiving slot, a pair of armature leads fastened therein, said segment being cut away at the point of attachment in such a manner that said leads enter the segment at points in different transverse planes, and means for mechanically and electrically connectingisaid leads together adjacent the end of the commuta-= tor segment but independent thereof.

2. In a commutator for dynamo electric 5 machinesfla commutator segmentprovided at one end with a lead receiving slot, a pair of armature leads fastened therein, and 

